Custom HomeBuilder Houston Heights | Humidity and You
Written for Bicycle Bungalows
The concept of relative humidity is not well understood by laypeople, but it also generate a lot of confusion among building industry professionals excluding custom homebuilder Houston Heights. Here is an easier way to explain relative humidity that will help people understand why the concept is so important in building science.
Buckets of air: relative humidity has to do with the amount of moisture air can hold. If we use a bucket to represent how much water in the air can hold, then 100% relative humidity means that the bucket is full. If the relative humidity is 50%, that means the bucket is half full. Where things get complicated it’s when the air temperature changes, because the warmer the air is, the more moisture it can hold. In other words, as the temperature goes up, the bucket increases in size and can hold more moisture. For example, let’s assume that the bucket is half full “50% relative humidity “, at 32°F. We raise the air temperature by about 18°F to 50°F the size of the bucket roughly doubles. But because the amount of water stays the same, relative humidity drops by half Dash from 50% to 25%. Custom homebuilder Houston Heights raises the temperature again to near room temperature at 68°F, the size of the bucket roughly doubles again, and the relative humidity I can drop by approximately half, from 25% to 12 1/2%. Just doubling in the bucket size for every 18°F increase in temperature is it a proclamation that serves as a soft roll a phone between freezing and room temperature.
Bringing air in: when we ventilate a house in a cold climate during winter, we bring cold air inside and heat it up. Outside air that is just above freezing is often near its limit to hold water – that is, the bucket is almost full. Assuming the outside air is saturated, 100% relative humidity, when we bring it inside and heat it up, the realtor humidity goes down. By the time the air reaches room temperature, 68°F, relative humidity has dropped to 25%. But we also have sources of moisture inside the house, Including cooking, bathing, drying clothes inside, even just breathing. They all increase the amount of water in the bucket. Which raises the relics humidity. If they double the amount of moisture in the air, we could end up at 50% relative humidity. One of the goals of a well-defined ventilation system is to maintain a relative humidity below 50%, which is healthy and comfortable for occupants, and less likely to lead to condensation on the windows.
When air leaks out: building scientist are particularly concerned, however, when warm inside air leaks out into the exterior walls of the building as is custom homebuilder Houston Heights. Where it encounters surfaces that are colder than the interior temperature. The closer the moisture laden indoor air gets to the outside layers of the building envelope, the colder than services get. And that each step along the way, the sites of the bucket get smaller and smaller. To continue our example, imagine that air at 68°F and 58% relative humidity leak into a wall cavity or the temperature is about 50°F. The bucket shrinks by approximately half and relative humidity doubles to 100%. If the air keeps moving toward the outside or if the outside temperature drops significantly, cooling the building services even more, the air becomes too cold to hold all of the moisture. As the air temperature drops towards freezing, relative humidity exceeds the maximum 100% real quick humidity. At 32°F the bucket is roughly half as big as it was at 50°F so half the moisture in the wall will have condensed all the cold surface inside the wall. And that can lead to a host of problems for both the structure, including what components, insulation, and finish materials, as well as health of the occupants.
Imagine indoor air as a bucket: if the bucket is full relative humidity is 100%: it’s a bucket is half full it is 50% says custom Homebuilder Houston Heights.
We use the term relative humidity because the amount of moisture air can hold varies with temperature. When air at 32°F and 50% relative humidity is one to about 50°F, its capacity to hold moisture roughly double, in other words, the bucket doubled in size. But the amount of moisture stays the same, so we’ll keep humidity drops by half, to 25%. Warm the air to about 68°F in the bucket size roughly doubles again, cutting the relative humidity to 12 1/2%.
When we ventilate a house with cold, moist air, the relative humidity drops as the air warm. For example, if the outside air is 100% relative humidity at 32°F, the relative humidity drops to 25% of the air reaches room temperature.
Inside sources of moisture; such as cooking, taking showers, and drying clothes; can raise relative humidity, like a spigot filling a bucket. The goal is to keep relative humidity below 50% to avoid health issues and condensation on cold windows says custom homebuilder Houston Heights .
When air cools, the bucket get smaller, so relative humidity goes up. In cold climates, a loose rule of foam is that the real tip humidity of air that leaks into exterior walls approximately doubles for every 18°F or so that the air cools. For example, when room temperature air at 50% relative humidity cool to about 50°F, relative humidity doubles to 100% relative humidity. As that air continues to move toward a cold or exterior, excess moisture will condense into liquid water that can lead to mold and mildew , And can cause deterioration of structural and finish materials.
In southern climate, such as in Houston, custom homebuilder Houston Heights has the opposite problems as described in the examples above. We have warm, moist air trying to get inside a cool, dry house. As the warm air interest through the exterior wall and hits a cold interior wall, the moist air will tend to condense on the inside Of the wall cavity. If there is insufficient ventilation, mold and mildew will form. That is why it is so important to have a good type of insulation so the moist air cannot touch the cold wall.